I applied online on a Tuesday. After completing the application, I was required to take an approx. 45 min test that measures mathematical aptitude, personality traits, and various other things. It was a bit boring and monotonous, but not overly difficult.
I received a call on Thursday to schedule a phone interview, which would take place the following Monday. The phone interview was surprisingly short, only about 10 - 15 minutes. It consisted of just going over my resume, my salary requirements, and one or two behavioral questions. The interviewer said they would forward the info onto the hiring manager who would then decide which candidates get an in person interview.
The next day, I received the a call from the local manager to have a face to face interview. The face to face interview took place on Thursday of that same week. There was a panel of three interviewers; however, only one person actually spoke, so it was more like a de facto 1 on 1 interview. It lasted about 90 minutes and heavily consisted of fairly standard behavioral questions. I would say, in total, I answered probably 10 questions. However, the manager was very laid back, upbeat, and definitely wholly involved. I've been to quite a few interviews where the interviewer seemed to just be going through the motions. Anyway, the interview seemed to be quite positive.
The very next day, Friday, I was called by the interviewing manager with an offer for the position.
Overall, it was a very, very quick process, consisting of 9 business days (from Tuesday of one week to Friday of the next). I came away with a very positive view of the company. As far as the office and work culture, the company seems to afford you a large amount of autonomy, yet still with a support structure if needed.
As far as interview advice, definitely study up on why you want to work for Liberty Mutual and have a fairly copious amount of past examples from your work history when you overcame a challenge, had to tell someone bad news, etc. Also, this was the third time I had interviewed with the company, so I can say that, as the old adage says, if at first you don't succeed, try, try again.
Good Luck.